Diving Deeper With ES6 Generators

8/11/2019 Diving Deeper With ES6 Generators

1/12

2.9.2014 Diving Deeper With ES6 Generators

http://davidwalsh.name/es6-generators-dive 1/12

Diving Deeper With ES6 Generators

By Kyle Simpson on July 27, 2014 162 25 10

The Basics Of ES6 GeneratorsDiving Deeper With ES6 GeneratorsGoing Async With ES6 GeneratorsGetting Concurrent With ES6 Generators

"Part 1: The Basics Of ES6 Generators"

function *foo () {

try {var = yield 3;

. log ( "x: " + ); // may never get here!}
http://dwf.tw/wufoohttp://davidwalsh.name/es6-generatorshttp://davidwalsh.name/concurrent-generatorshttp://davidwalsh.name/async-generatorshttp://davidwalsh.name/es6-generators-divehttp://davidwalsh.name/es6-generatorshttp://getify.me/


2/12



catch ( ) {. log ( "Error: " + );

}}

var = foo ();

var = . next (); // { value:3, done:false }

// instead of resuming normally with another `next(..)` call,// let's throw a wrench (an error) into the gears:

. throw ( "Oops!" ); // Error: Oops!

function *foo () { }

var = foo ();try {

. throw ( "Oops!" );}catch ( ) {

. log ( "Error: " + ); // Error: Oops!}


3/12



function *foo () {var = yield 3;var = . toUpperCase (); // could be a TypeError error!

yield ;}

var = foo ();

. next (); // { value:3, done:false }

try {. next ( 42 ); // `42` won't have `toUpperCase()`

}catch ( ) {

. log ( ); // TypeError (from `toUpperCase()` call)}

function *foo () {yield 3;yield 4;

}

function *bar () {yield 1;yield 2;

yield *foo (); // `yield *` delegates iteration control to `foo()`yield 5;

}


4/12



for ( var bar ()) {. log ( );

}// 1 2 3 4 5

function *foo () {var = yield 3;var = yield 4;

. log ( "z: " + + ", w: " + );}

function *bar () {var = yield 1;var = yield 2;yield *foo (); // `yield*` delegates iteration control to `foo()`


5/12



var = yield 5;. log ( "x: " + + ", y: " + + ", v: " + );

}

var = bar ();


. next ( "X" ); // { value:2, done:false }

. next ( "Y" ); // { value:3, done:false }

. next ( "Z" ); // { value:4, done:false }

. next ( "W" ); // { value:5, done:false }// z: Z, w: W

. next ( "V" ); // { value:undefined, done:true }// x: X, y: Y, v: V

function *foo () {yield 2;yield 3;return "foo" ; // return value back to `yield*` expression

}

function *bar () {yield 1;var = yield *foo ();

. log ( "v: " + );yield 4;

}

var = bar ();




. next (); // "v: foo" { value:4, done:false }

. next (); // { value:undefined, done:true }


6/12


7/12



. throw ( "Uh oh!" ); // will be caught inside `foo()`// foo caught: Uh oh!

. next (); // { value:undefined, done:true } --> No error here!// bar caught: Oops!


8/12



getify.me getify posts

Recent Features

CSS filters

Incredible Demos

five awesome Mozilla technologies that most people have neverheard of
http://davidwalsh.name/facebook-meta-tagshttp://davidwalsh.name/mozilla-technologieshttp://davidwalsh.name/togetherjshttp://davidwalsh.name/tutorials/demoshttp://davidwalsh.name/canvas-demoshttps://dvcs.w3.org/hg/FXTF/raw-file/tip/filters/index.htmlhttp://davidwalsh.name/css-filtershttp://davidwalsh.name/tutorials/featureshttp://dwf.tw/ydkjsallhttp://davidwalsh.name/author/kylesimpsonhttp://twitter.com/getifyhttp://getify.me/


9/12



Discussion

yield *

function * gen (){yield * [ "a" , "b" , "c" ]

}

gen (). next () // { value:"a", done:false }
http://getify.me/http://webplatformdaily.org/http://getify.me/http://twitter.com/ziyunfeihttp://www.ifeenan.com/


10/12


http://getify.me/http://atomictumato.blogspot.com/http://www.brandingly.org/http://atomictumato.blogspot.com/


11/12



Name Email Website

Post Comment! Use Code Editor


12/12


Documents

Diving Deeper With ES6 Generators